My mitigation to Wine bug 43030

line-helper.service

#How to setup:
#1. Have systemd and xdotool installed
#2. store the script (Line_helper.sh) as $HOME/.local/script/Line_helper.sh
#3. store this service file as $HOME/.config/systemd/user/line-helper.service
#4. chmod +x $HOME/.local/script/Line_helper.sh
#5. start line-helper.service before you start line

[Unit]
Description=Automatically minimize Line
After=graphical.target

[Service]
ExecStart=%h/.local/script/Line_helper.sh
Restart=always
RestartSec=30

[Install]
WantedBy=default.target

Line_helper.sh

#! /bin/sh

if [[ $(which xdotool) = "" ]]; then
        echo "xdotool is required to run this script."
        exit
fi

if [[ $(which xwininfo) = "" ]]; then
        echo "xwininfo is required to run this script."
        exit
fi

while true
do
    xwininfo -tree -root |
        grep 'has no name.*"line.*\.exe"' |
        awk '{ print $1 }' |
        xargs -rl xdotool windowclose
    sleep 10
done

A example on how to start systemd service with Line. (I use Lutris to setup Line)

I use this script to kill LINE's borders:

xwininfo -tree -root |
   grep 'has no name.*"line.*\.exe"' |
   awk '{ print $1 }' |
   xargs -rl xdotool windowclose

That works very well without the need to minimize Line, thank you!